Scientific Method —

Manufacturing universes in a fractal multiverse

Discussions at the World Science Festival tackled everything—literally. …

The World Science Festival likes to tackle big ideas, and this year was no exception, with a session devoted to everything—more specifically, why our Universe is here and whether it might be part of a larger whole. This isn't the easiest of topics, even for someone who's followed science carefully for the last few years, but the panelists did an admirable job of making their presentations reasonably approachable. It seems that the easiest way to explain the existence of our Universe may involve a process that will inevitably produce an infinite number of other universes. The details, however, are considerably more complicated.

Those details, or at least an accessible version of them, were provided at the the Infinite Worlds program. The moderator, Robert Krulwich of WNYC's RadioLab, did an commendable job by pointing out there was no scientific consensus on the idea that there may be infinite universes out there, but the panel only included advocates; to provide a hint of balance, he read quotes from some of its critics at various points in the discussion.

That turned out to have a valuable function in that it pointed out two sources of confusion. One is that the formation of the Universe isn't the only context in which theoreticians have started suggesting there might be many of them. In an unrelated area of study, some have suggested multiple universes as a way to resolve our discomfort over the fact that, on a quantum level, single particles and photons appear to be able to be in two places at the same time—in this view, they do wind up in two places, just in different universes that diverge and rejoin to produce the apparent quantum effect.

For the topic at hand, however, the use of the term "universe" also gets a bit slippery. Does it mean our own, familiar universe, which may be one of an infinite number of similar items? Or does it apply to the larger whole, within which those items are an inevitable result of the process of inflation?

For our purposes, we'll call the larger whole the multiverse, and its resident bits of inflation universes, one of which is our own, which will be capitalized. To understand the multiverse, you've got to understand inflation, and for that, the panel had Alan Guth, who was instrumental in developing it as a concept. The basic idea of inflation is that, early in the Universe's history, it went through a period where it expanded at a staggering rate. Prior to this inflation, the Universe was compact enough for things to interact in a way that smoothed out things to their current level of lumpiness, while the field that drove inflation decayed when the Universe was roughly "the size of a marble," according to Guth. Inflationary models have since been used to make predictions that were confirmed by the COBE and WMAP probes, which explored the cosmic microwave background.

Guth briefly touched on the personal aspects of developing his theory, saying it was six months of hard work and lucky encounters with other scientists and ideas, followed by "one good night" where things fell together. Another panelist, Andrei Linde of Stanford, said he happened to get a key insight while at home, and had to call a colleague from the bathroom, so he could have someone check the outlines of his ideas without waking his son. When his ideas cleared that hurdle, he got excited enough that he, "woke my wife and told her 'I think I know how the Universe was created.'"

Linde was working on inflation from the perspective of what's called the "graceful exit" problem: how do you get inflation that's just enough to blow up the Universe, but stops before ripping it apart? The answer Linde eventually came up with is that sometimes you do, sometimes you don't. This is where the idea of a multiverse comes in. The fabric of the multiverse is an inflationary field that's filled with quantum fluctuations. These fluctuations can interfere with each other, creating high inflation at the peaks. The low points of the interference are where stable universes can pop out of the field. Conveniently, the high points continue to inflate, producing more multiverse fabric, which undergoes its own quantum fluctuation, making it an endless producer of universes; Linde describes it as a fractal process.

Festival founder Brian Greene was on hand to mention why, as a string theorist, the multiverse was very satisfying to him. In short, string theory has been suffering from its own inflation, as it looks like there are 10 or 11 extra dimensions beyond the four familiar ones of space-time. How those extra dimensions get compacted away determines the physical properties of our Universe. Over a decade ago, Greene was hoping something would come out of the math that would explain why we have the properties we do, but now he accepts that we're living in a universe with just one out of over 10500 potential combinations of properties.

The nice thing about the multiverse is that each of the universes it spews out should have its own set of physical rules. So, in short, if the process really is infinite, a universe with our properties was pretty much inevitable. In fact, something with a value for dark energy that's similar to our own universe appears in somewhere around 10300 of the possible types of physics predicted by string theory.

The panel helpfully included a philosopher of science (Nick Bostrom), who noted that all of this is nice, but ultimately we wanted something with testable consequences. Currently, the multiverse ideas don't have a guaranteed, testable prediction, but they do have at least one potential consequence. Early in our Universe's history (before the mulitiverse's inflation pulled things apart), it was possible that the Universe bumped into a neighboring one. If that's the case, there should be remnants of that event buried in the cosmic microwave background. Less than a month from now, the ESA's Planck mission should arrive at the L2 Lagrange point with instruments sensitive enough to pick up this signal.

Overall, the program was really appealing, both because it tackled big issues, and because the scientists talked a bit about their personal road to their ideas, which undoubtedly helped the audience connect a bit. The seats in my immediate vicinity contained a physicist, a corporate lawyer, and actress Cameron Diaz, so it clearly drew a diverse crowd—just the sort of thing the World Science Festival was aiming for.

24 Reader Comments

I was always told that the answer to the question "What is the Universe expanding into?" was "Nothing, the space itself is expanding." Does this mean that that isn't actually the case, and that the Universe is expanding into this 'multiverse fabric'?

Or am I still just trying to wrap my 3-dimensional brain around multi-dimensional concepts and failing?

Or am I still just trying to wrap my 3-dimensional brain around multi-dimensional concepts and failing?

er, kind of. The other universes aren't beyond our universe in the 3D space. That is, if you keep moving in our universe for infinite amount of time, you WON'T bump into another universe. Imagine an infinitely large whiteboard, which an insect is moving on and it can't leave it. And suppose you're observing it. The insect can keep moving for infinite amount of time, but it won't be able to reach you because it can't leave the 2D space of the whiteboard. For it to reach you, it will have to travel in a new (3rd) spatial dimension. Similarly there are other spatial dimensions according to the theory. And the whiteboard can keep expanding, but it won't bump into other whiteboards that are placed on another wall.

Originally posted by ewelch:"An infinite number of monkeys hitting at an infinite number of typewriters for an infinite amount of time will eventually produce all works of Shakespeare."

Um, no, it would happen instantly. Your definition of infinite is too small.

Yep - a finite amount of monkeys typing for an infinite amount of time will *eventually* produce the complete works of Shakespeare.

For that matter, a finite number of monkeys typing away will *immediately* start producing the complete works of Shakespeare. Just not with all the letters in the correct order.

An infinite number of monkeys will produce the collected works of Shakespeare in the smallest feasible time it takes to produce the most time-consuming of his works(or portion of any of his works, if one permits the concatenation of partial works between monkeys -- which at its logical extreme, is the smallest amount of time a monkey can require to press one key).

"An infinite number of monkeys hitting at an infinite number of typewriters for an infinite amount of time will eventually produce all the works of Shakespeare."

Assuming this was possible, what would it prove? That random associations given enough time equal genius? Were the works of Shakespeare reproduced thus, the mere words wouldn't mean the same - because the purpose of words is to convey meaning. Thus while the words of Shakespeare might be reproduced thus, the works of Shakespeare couldn't be.

Shakespeare is Shakespeare because his words cut through the apparently random meaninglessness of existence. With the Bard at least, the journey is the reward and the monkey theory is simply the wrong journey.

The fact that we have Shakespeare rather than monkeys tells us that the universe has shortcuts to patterned complexity rather than a random set of infinite options exercised blindly. Conjecture as much as you like, the reality is that we have Shakespeare and not the monkeys as the actual way the universe works. This means that the cosmos is pre-primed for meaningful associations from subatomics to Shakespeare.

With regard to the universe expanding into "Nothing": time, space and matter are all part of the same tight, but expanding package. Even 'Nothing' can't exist beyond it. But that isn't to say there aren't more layers to the package that are simultaneously expanding and interacting with our layer in a fundamental way.

Imagine the package as a number of sheets of paper all screwed up together into a ball which is slowly expanding as a result of the combined pressure of all of the sheets, and that our universe is just one sheet. Because we only see the bits of the fundamental interactions of the sheets that involve our piece of the multi-layered wrapping, we observe the apparent irrationality of the quantum effect. If we could see all the sheets, our parts of their combined interaction wouldn't be so mysterious. But we can't detect the parts of these interactions that aren't on our universe's sheet.

Perhaps if we got a whole lot of monkey-powered keyboards, I wonder if we couldn't bash out a theory of everything in less time than it would take to randomly do Hamlet?

I realise... I was looking at the rationale for the whole argument itself which I'm pretty sure traces its roots back to an old anti-creationist proposition, that given enough time anything is possible. It's not unlike a logical blank check.

The infinity idea seems to me to be something you can neither logically attack nor defend and so I looked at the purpose for the argument itself.

On that tack I wonder if the monkey idea isn't having at least a slight renaissance with what seems to be an infinite mulitiverse carte blanche approach. It's a very fine balance of functional principles that allows our particular universe to survive in a form that fosters intelligent life and if we could see the whole picture, that balance might seem infinitely more improbable.

Because of the fundamental interrelatedness of a multiverse of which ours seems to be a part, I think it's likely that whatever else is out there can't simply be random.

Originally posted by peter.c:The fact that we have Shakespeare rather than monkeys tells us that the universe has shortcuts to patterned complexity rather than a random set of infinite options exercised blindly. Conjecture as much as you like, the reality is that we have Shakespeare and not the monkeys as the actual way the universe works. This means that the cosmos is pre-primed for meaningful associations from subatomics to Shakespeare.

Really? Please explain, as that's quite an assertion to make with no explanation. "A blind watchmaker, by any other name, would smell as godly"

And would I somehow react differently reading a work if I didn't know whether it was written by Shakespeare or a barrel of monkeys? I don't think so.

Originally posted by peter.c:The fact that we have Shakespeare rather than monkeys tells us that the universe has shortcuts to patterned complexity rather than a random set of infinite options exercised blindly. Conjecture as much as you like, the reality is that we have Shakespeare and not the monkeys as the actual way the universe works. This means that the cosmos is pre-primed for meaningful associations from subatomics to Shakespeare.

Really? Please explain, as that's quite an assertion to make with no explanation. "A blind watchmaker, by any other name, would smell as godly"

And would I somehow react differently reading a work if I didn't know whether it was written by Shakespeare or a barrel of monkeys? I don't think so.

I thought it was now at least fairly well-accepted that evolution is directed rather than haphazard. You don't need to believe in a Deity to accept that - and most don't. But the universe isn't blindly random in the laws that underpin such processes either. Everything is causally linked, and so it would be irrational to assume that there was at some point in the universe's fabric a disjunction that shifted away from a continuous series of increasingly complex steps, toward meaning.

Our cosmos could have been grey goo but the balance of its fundamental principles is weighted toward one that sustains intelligent life and not simply grey goo or mindless matter. If the balance is even as fine as say 1% away from grey goo toward what we have, that is still a bias toward the sustenance of systems that in turn sustain meaning.

I accept your opinion re Shakespeare, but I'm afraid I would react differently to a work written about the triumph, poetry and pathos of human existence that distilled essential truths from meaningful experience, than one that appeared by random accident from a different species that was unable to even understand what it had written.

Look, you give me an infinite amount of monkeys, an infinite amount of typewriters and paper and an infinite amount of time and what happens?

Not only will they produce the complete works of Shakespeare, but that of Plato, the Bible, the Koran, all of Stephen Kings works, even Britney Spears biography. The complete script of every espisode of friends, including those never actually filmed. They will even create every post on every forum that you or I have wrote. Even this very thread will be reproduced (along with the adverts at the side too)

Not withstanding that in all that 99.999 reacurring will be complete garbage and meaningless jumbles of letters, I completely fail to understand why you would want to spend an infinite amount of time trying for find Shakespeare amongst it all when the collection will also contain all the correct forumlas and knowledge of how the universe is created and how it functions. Surely it makes more sense to look for this rather than Hamlet.

The multiverse idea is already supported by maths at the elementary level.

infinity divided by infinity equals one. However there are an infinite amount of ones.

10 divided by 3 I find interesting.

You would need more time than exists to complete the function. How much time exactly? Not much. In fact an infinitesmally little bit extra amount of time would be enough. Shame you have run out of the stuff really as you wouldn't believe just how much little you needed.

Don't you find it fascinating that the length of time needed would be infinitesmally big yet the extra required would be infinitesmally small. Trust me, we need to solve this problem as it is the key to how the Universe works.

Of course, you can solve the issue of 10 divided by three without running into the barrier of always requiring a smaller and smaller amount of extra time at any point. You have to make a sacrifice. (No, not that kind, all you Virgins feel free to relax). You have to make an uneven universe.

One of the three will have to have a little bit more than the other two. The other two are equal, but one has to be just that bit more. You could make that call just before you get to the edge of infinity so that the difference between them is negligable it 'almost' irrelavent.

Thus the only way you can solve this problem so that the results are as even as possible is just immediatley before infinity or immediately after it.

infinity divided by infinity equals one. However there are an infinite amount of ones.

No it doesn't. Not if you know calculus/limits. limit of x^2/x, where x tends to infinity is equal to infinity, while the numerator and denominator are both infinity. On the other hand, if you consider limit of x/x^2 as x tends to infinity, it is zero.

quote:

10 divided by 3 I find interesting.

You would need more time than exists to complete the function.

you need infinite time to write it, that is, encrypt the information in the form of symbols. Do it in base three. 10/3 in base 3 is equal to 10.1, no recurring decimal. So it depends on the method used to encrypt the info.

infinity divided by infinity equals one. However there are an infinite amount of ones.

No it doesn't. Not if you know calculus/limits. limit of x^2/x, where x tends to infinity is equal to infinity, while the numerator and denominator are both infinity. On the other hand, if you consider limit of x/x^2 as x tends to infinity, it is zero.

quote:

10 divided by 3 I find interesting.

You would need more time than exists to complete the function.

you need infinite time to write it, that is, encrypt the information in the form of symbols. Do it in base three. 10/3 in base 3 is equal to 10.1, no recurring decimal. So it depends on the method used to encrypt the info.

By switching to base 3 you changed the numbers the point was about, with the number not the symbols the same point can be made in base three 101/10.

Limits in calculus are there to remove infinity from equations , this use of math does not change the point.

By switching to base 3 you changed the numbers the point was about, with the number not the symbols the same point can be made in base three 101/10.

Limits in calculus are there to remove infinity from equations , this use of math does not change the point.

edit: syntax

What point did I not change? I mean what point is it, exactly?

Also, I understand that the same thing can be said for 101/10 for decimal numbers, but what you're talking about is just because of the way we represent information. You could decide to always use base equal to the denominator to represent recurring decimals. The infinite number of digits isn't inherent in the fraction itself, but it is due to the way we represent information.